This invention relates to a plough for winning material such as coal, from a mineral face or seam in a mine working.
In order to win coal in the roof zone of a mine working, particularly in seams of varying thickness, it is known to provide coal ploughs with roof cutters mounted on a vertically adjustable carrier. Such a carrier may be held against the roof of the mine working by, for example, compression springs, hydraulic rams, or by manually adjustable displacement devices such as spindle-actuated thrust rods or lever-actuated ratchets. (see DE-PS No. 1,170,350, DE-OS No. 2,518,221 and DE OS No. 2,309,820)
Known displacement devices have the disadvantage that they require a relatively large space for their installation on the plough body, and particularly for short ploughs, such space is often not available. A further disadvantage of known displacement devices is their susceptibility to contamination and corrosion which adversely affects their efficiency. Moreover, the known displacement devices can only be adjusted in discrete steps.
The aim of the invention is to provide a plough having a displacement device for the carrier of its roof cutters, which displacement device does not suffer from these disadvantages.